Method of imparting wet and dry crease recovery to cellulose textile fabric



United States Patent 3,173 750 METHOD SF IIVIEARTING WET AND DRY GREASE RECOVERY T ELLULOSE TEXTKLE FABRIQ Fred L. McDowell, H12, Spartanburg, S.C., assignor to Deering Miiliken Research Corporation, Spartanhurg, S.C., a corporation of Delaware No Drawing. Filed Get. 19, 1969, Ser. No. 63,503 Hi Claims. (til. 8-416) This invention relates to a chemical process for the wet cross linking of cellulosic textile materials to impart min mum care characteristics thereto. More particularly, it relates to a process for wet cross linking of such materials with an alkaline catalyzed wet cross linking agent While the fibers thereof are Wet with a trialkali-metal salt of phosphoric acid.

In Belgian Patent 556,279 there is disclosed a method of wet cross linking cellulosic fabrics to produce a flat drying fabric having improved wet crease recovery, i.e., the fabric when passed through the spin cycle of an automatic washer and then line dried is obtained essentially wrinkle free. In US. Patent 2,524,399 another method of Wet cross linking fabrics is disclosed employing divinyl sulfone. However, both of these processes do not produce fabrics having good dry crease recovery, i.e., the fabric when tumble dried in a drier or otherwise creased in the dry state is obtained in a wrinkled condition. This lack of dry crease recovery in the wash and wear characteristics of the fabric limits somewhat the methods of washing the fabrics so that they can be obtained in a wrinkle free state.

It is an object of this invention to provide a method of wet cross linking cellulosic textile material so that both improved wet crease recovery and dry crease recovery is imparted to the treated material.

Another object is the provision of a process of wet cross linking cellulosic fabric so that the treated fabric can be spin dried in an automatic washer and then tumble dried in'an automatic drier to a wrinkle free condition.

These and other objects which will be apparent to those skilled in the art are achieved by wet cross linking a cellulosic textile material with an alkaline catalyzed wet cross linking agent, while the fibers thereof are wet with an aqueous solution containing a substantial amount of a trialkali-metal salt of phosphoric acid.

It is essential that the dry cellulosic fibers be wet with one of the aforesaid salt solutions. This cannot be achieved if the cellulosic fibers are already wet with water or other solvent which causes the fibers to swell before being contacted with one of these salt solutions. If the material is first impregnated with an aqueous solution of the cross linking agent or catalyst and the trialkalimetal salt then applied to the material, improved dry crease recovery in the cross linked material is not obtained, even though the process is otherwise identical with the process claimed herein and identical amounts of the same salt are employed.

Thus, this invention is limited to those processes in which the dry textile material is contacted with an aqueous solution of the selected salt. The selected cross linking agent, and catalyst if additional catalyst is required, can thereafter be applied. More conveniently, the selected salt and catalyst are applied simultaneously as a mixed aqueous solution thereof. A further alternative involves applying the cross linking agent to the fabric material under conditions which do not cause significant swelling of the fibers, i.e., maintaining the fabric dry, and thereafter applying the aqueous solution of the selected salt followed by or concomitantly with any additional alkaline catalyst for the cross linking reaction.

Surprisingly, it has been found that salts other than the trialkali-metal salts of phosphoric acid do not possess this ability to impart dry crease recovery to wet cross linked cellulosic materials. For example, sodium sulfate and sodium acetate are lacking in this property.

While the improved dry crease recovery in the cross linked material begins to be apparent when the material is wet with solutions containing as little as 10% by weig t of the selected salt, optimum results are obtained when the solution contains at least 15 to 20%, more referabiy at least 25% and most desirably 30% to 40% or more of the selected salt.

in carrying out the process of this invention, a dry cellulosic textile material as defined hereinafter is wet with an aqueous solution containing the desired concentration of a trialkali-metal phosphate in an amount sufiicient to provide the desired solution pick-up on the fabric and is then reacted with the selected alkaline catalyzed wet cross linking agent to produce material having both wet and dry crease recovery.

The term ceilulosic material when used herein means any material, preferably textile, comprising fibers having the free hydroxy groups characteristic of cellulose, e.g., cotton, unmodified cellulose and cellulose modified by etherifica-tion or esterification of a portion of the hydroxy groups. Textile materials within this definition include those comprising natural cellulose fibers, e.g., cotton, linen, jute, flax, regenerated cellulose fibers, e.g., viscose rayon fabrics, and cellulosic fibers some of the hydroxy groups of which have been replaced by ester or ether groups, as long as some free hydroxy groups are present so as to obtain the desired cross linkage. Normally, cellulosic fibers which contain as few as 1.8 free hydroxy groups per anhydro-glucose unit will result in sufiicient cross linkage for satisfactory results. Thus, cellulosic textile materials the fibers of which contain a limited number of acetyl groups, such as cellulose acetate, or textile materials the fibers of which contain a limited number of ether groups, such as partially methylated cellulose, can be processed according to this invention. However, textile materials which do not comprise cellulosic fibers having free hydroxy groups are not normally suitable for use in the process of this invention and are not within the term cellulosic material as used herein.

Although this invention is directed primarily and preferably to cellulosic textile fabrics, both knitted and woven, the advantages of this invention can also be achieved by treating the cellulosic yarns or threads employed to produce these fabrics. Ordinarily, this will be cotton thread or yarn. 1 he thus treated thread or yarn, when Woven into fabric, will produce a fabric having better minimum care properties than identical fabric woven from yarn or thread resin treated according to prior art procedures.

Satisfactory results, according to this invention, can be achieved employing cellulosic fabrics containing both cellulosic and noncellulosic fibers, especially if the nonceilulosic fibers have some minimum care characteristics of their own. For example, the minimum care characteristics of fabrics formed from a mixture of glycolterephthalate fibers and cotton fibers can be improved by the process of this invention even if the percentage of cotton fibers is small, e.g., to 40%. Satisfactory results can be obtained with fabrics formed from a mixture of nylon fibers and cellulosic fibers or a mix ture of cellulosic fibers and polyacrylic fibers, e.g., those sold under the trademark Orlon. The improved characteristics of the fabric treated according to the process of this invention will be more readily apparent if the cellulosic, e.g., cotton, content of the fabric is substantial, e.g., about 40% or more by weight.

Because woven fabrics consisting essentially of cotton, e.g., 90100% cotton, are the ones more frequently treated with a crease proofing agent, i.e., cross linked, it is to these fabrics that this invention is preferably directed.

The process of this invention involves the use of alkaline catalyzed wet cross linking agents under conditions which will impart substantial wet crease recovery, i.e., spin flat drying properties, to the material. Many of these agents are known in the art. The preferred wet cross linking agents are those containing from 3 to carbon atoms, inclusive, e.g., those which produced cellulosic cross linkages of from 3 to 6 carbon atoms in length. The bridging chain formed by the cross linking agent can contain, depending on the choice of wet cross linking agent, elements other than carbon and, in fact, in all instances the cross linkage will contain oxygen as the cross linkage as a result of etherification of hydroxy groups of the cellulose. In addition to oxygen and carbon, the linkage may also contain nitrogen, phosphorous, sulfur, silicon, or other polyvalent elements known to form stable organic linkages. Likewise, the cross linkage may contain substituent groups or side chains. Examples of substituent groups which may be present include keto groups, hydroxy groups, halogen atoms, and methyl groups, although the presence of such substituent groupsordinarily is not preferred and the number and size of these substituent groups should be such that the molecular weight of the divalent radical connecting the cellulose-reactive groups of the cross linking agent is not in excess of about 260. It should also be emphasized that the preferred alkaline catalyzed wet cross linking agents, while spoken of as having two or more reactive groups, need not possess groups, as it is initially employed in the process of this invention, which are capable of reacting directly with hydroxy groups. The reactive groups can suitably be transformed in situ as a result of the action of the basic catalyst to give connective groups capable of reacting with cellulose, as in the case of halohydrins.

Alkaline catalyzed, wet cross linking agents within the above general classification can be divided into three general classes. A first class comprises the polyepoxy cross linking agents or their equivalents. This class of cross linking agents includes diepoxybutane; the diglycidyl ether of ethylene glycol, propylene glycol, or diethylene glycol; the triglycidyl ether of glycerol; and the diglycidyl ether of bisphenol A. Compounds which are, in some respects, equivalents of the polyepoxy cross linking agents and which fall within the same general class of compounds having an tat-halohydrin group, e.g., chlorohydrin or brornohydrin, in place of one or more of the epoxy groups and compounds having a halogen atom, e.g., chlorine or bromine, on a carbon atom adjacent either an epoxy group or a halohydrin group. Examples of such compounds are epichlorohydrin, 1,3-dichloropropanol-2, 1,3-dibromopropanol-2, and bis-(1-chloro-2-hydroxy-n propoxy)ethane. A second class of preferred alkaline catalyzed wet cross linking agents include the sulfone activated divinyl compounds. Examples of this class of compounds are divinyl sulfone, divinyl sulfoxide, bis- (vinyl sulfonyl)methane, 1,4-bis-(vinyl sulfonyl)butane, disodium bis- (sulfatoethyl -sulfone, disodium bis- (sulfatoethyl) sulfoxide and the corresponding ammonium salts. A third class of alkaline catalyzed wet cross linking agents are the carbonyl activated divinyl compounds, e.g., divinyl ketone, and octa-1,7-diene-3,6-dione.

As described in Belgian Patent 556,279, to obtain flat drying properties with some of the above-described wet cross linking agents it is necessary to limit the amount of water present during the reaction. With, e.g., the halohydrins, a-haloepoxides and diepoxides, it is necessary that the amount of water present be no more than 130% and preferably less than 100% of the dry weight of the material being treated. On the other hand, with divinyl sulfone and divinyl sulfoxide, the flat drying properties can be imparted to the material in the presence of greater amounts of water.

The selected trialkali-metal phosphate, being alkaline, can act as the sole alkaline catalyst. alyst is employed, e.g., an alklali-metal hydroxide or other strong alkaline catalyst, the amount can vary considerably. An amount less than about 13% and ordinarily less than 10% is employed. As the alkaline catalyst is ordinarily applied as an aqueous solution of the dry material, these amounts are conveniently expressed in terms of concentration of the aqueous catalyst solution. Thus; an aqueous catalyst solution of the catalyst of between about 0.5% and about 16% concentration will ordinarily provide the desired amount of catalyst, the exact concentration being governed in part by the catalyst, the amount of the solution applied to the material, and the selected wet cross linking agent.

If the cross linking agent consumes two chemical equivalents of alkaline catalyst, as in the case of 1,3-dichl0ropropanol-2, then about 1.5 to 2.5 chemical equivalents of catalyst, calculated in the amount of cross linking agent applied to the material, can suitably be employed. If a cross linking agent is employed which consumes only a chemical equivalent of alkaline catalyst, as in the case of epichlorohydrin, then about 0.5 to 1.5 chemical equivalents of catalyst, calculated in the amount of cross linking agent applied to the material can be employed. With wet cross linking agents which do not consume the catalyst, e.g., the diepoxides and divinyl sulfone, correspondingly lesser amounts can be employed, and desirably the selected trialkali-metal phosphate can be employed as the sole catalyst. For example, excellent results are obtained using 8% to 12% epichlorohydrin as the wet cross linking agent, calculated on the weight of the dry material, and between about 2.5% and 3.5% of sodium hydroxide, calculated on the weight of the dry material, as

a 3.5% to 4.5% aqueous solution With an to uptake thereof. A stoichiometrically equivalent amount of another alkali metal hydroxide gives comparable results.

The reaction times and temperatures employed in the process of this invention are the same as the corresponding processes of the prior art performed where the fabric is not wet with an aqueous solution of a trialkali-metal phosphate.

The following examples are illustrative of the process of this invention but are not to be construed as limiting.

Example I 4.0 yards/lb. 80 x 80 dry print cloth Was wet with aqueous solutions of potassium hydroxide containing various percentages of tripotassium phosphate, calculated on the weight of the solution. The fabric was passed through squeeze rolls to provide a wet pick-up of about 80%, calculated on the weight of the dry fabric. The wet fabric was then passed over an applicator roll which applied thereto about 810% epichlorohydrin to the wet fabric, calculated on the weight of the dry fabric. The fabric was collected in a smooth roll, sealed in a plastic bag and maintained for 4 hours at 55 C. The fabric was washed thoroughly, dried and then assayed for fiat drying properties according to A.A.T.C.C. Test Designation T881958. The results of these experiments are shown in the table below.

If additional cat Flat Dry Rating 1 Percent KOH Percent K31 Spin Plus Spin Plus Line Dry Tumble Dry 1 Average of 9 ratings.

From the above results, it can be seen that when the cross linking reaction is conducted when the fabric is Wet with an aqueous solution not containing a trialkalimetal phosphate, there is obtained cross linked fabric (Controls) having substantially the same dry crease recovery, -i.e., the tumble flat drying properties, as untreated cotton fabric, whereas when the same reaction is conducted while the same fabric is wet with solutions con taining substantial amounts of a trialkali-metal phosphate, fabric having substantial tumble flat drying properties is obtained.

Similar results are obtained when equivalent amounts of trisodium phosphate are substituted for tr-ipotassium phgrsphate.

Example II Following the procedure of Example I, similar results are obtained employing potasium hydroxide, substituting dichloropropanol for the epichlorohydrin and employing the same amounts of tripotassium phosphate as shown in Example I. The resulting fabric, except the controls, has tumble fiat drying properties as well as spin flat drying properties.

Example 111 Results similar to those obtained in Example I are obtained by employing 2 /2% potassium hydroxide, substituting butadiene diepoxide for the epichlorohydrin and, employing the same amounts of tripotassium phosphate as shown in Example I. All of the resulting fabrics have tumble as well as spin flat drying properties.

Example IV Fabric having both dry and wet crease recovery is obtained by employing 2% potassium hydroxide and substituting for the epichlorohydrin an aqueous solution of divinyl sulfone that provides a 4% pick-up of divinyl sulfone, calculated on the weight of the dry fabric.

Similarly, divinyl ketone can be substituted for the divinyl sulfone.

Example V Fabric having dry crease recovery as well as wet crease recovery is obtained if an equal weight of disodium bis- (sulfatoethyl)sulfone is substituted for the epichlorohydrin in Example I, it being applied as a mixed solution with the sodium hydroxide.

Similarly, disodium bis(sulfatoethyl)sulioxide can be substituted for the disodium bis(sulfatoethyl)sulfone.

What is claimed is:

1. In a method of imparting improved wet crease recovery to a cellulosic textile material by reaction, while the fibers thereof are in a Wet, swollen condition, with an alkaline catalyzed cross linking agent which ordinarily imparts increased wet crease recovery but substantially no increased dry crease recovery to said material, the im provement which comprises conducting said cross linking reaction while said material is Wet with an aqueous solution containing at least 10% by weight of a trialkalimetal phosphate whereby said textile material has im parted thereto both improved wet and dry crease recovery properties.

2. The method of claim 1 wherein the textile material is a fabric consisting essentially of cotton.

3. The method of claim 1 wherein the trialkali-rnetal phosphate is tripotassium phosphate.

4. In a method of imparting improved wet crease recovery to a textile fabric consisting essentially of cotton by reaction, while the fiber of said fabric are in a wet, swollen condition, with an alkaline catalyzed cross linking agent which ordinarily imparts increased wet crease recovery but substantially no increased dry crease recovery to said fabric, the improvement which comprises conducting said cross linking reaction while said fabric is wet with an aqueous solution containing at least 25% by weight of a trialkali-metal phosphate whereby said textile material has imparted thereto both improved wet and dry crease recovery properties.

5. The method of claim 4 wherein the trialkali-rnetal phosphate and an additional alkaline catalyst are applied simultaneously to the dry fabric as a mixed aqueous solution thereof, prior to the cross linking agent.

6. The method of claim 4 wherein the trialkali-metal phosphate is tripotassium phosphate.

7. A method of imparting improved wet and dry crease recovery to a cotton textile fabric which comprises wetting the dry fabric with an aqueous solution comprising an alkaline catalyst for the reaction and from 20 to 45% by weight of a trialkali-metal phosphate and thereafter applying to the thus wet fabric from about 3 to 30%, by weight of the dry fabric, of a cross linking agent select ed from the group consisting of polyepoxides, dihalohydrins, epoxyhalohydrins, a-haloepoxides, and sulfone and carbonyl activated divinyl compounds and curing said cross-linking agent on the fabric while the fibers thereof are in a wet swollen condition whereupon both improved wet and dry crease recovery properties are imparted to the fabric, whereas, in the absence of the trialkali-metal phosphate, only improved wet crease recovery properties would be obtained.

8. The process of claim 7 wherein the cross linking agent is epichlorohydrin.

9. The process of claim 7 wherein the agent is 1,3-dichloropropanol.

10. The process of claim 7 wherein agent is divinyl sulfone.

cross linking the cross linking References Cited in the file of this patent UNITED STATES PATENTS 2,609,270 Couper Sept. 2, 1952 2,730,427 Suen Jan. 10, 1956 2,985,501 Gagarine May 23, 1961 3,061,399 Tesoro et al Oct. 30, 1962 OTHER REFERENCES Van Wazer: Phosphorus and Its Compounds, vol. 1, 1958, page 497, Interscience Publishers, Inc., N.Y.

Textile Research Journal, vol. 30, Jan. 1960, pp. 72 and 73. 

1. IN A METHOD OF IMPARTING IMPROVED WET CREASE RECOVERY TO A CELLULOSIC TEXTILE MATERIAL BY REACTION, WHILE THE FIBERS THEREOF ARE IN A WET, SWOLLEN CONDITION, WITH AN ALKALINE CATALYZED CROSS LINKING AGENT WHICH ORDINARILY IMPARTS INCREASED WET CREASE RECOVERY BUT SUBSTANTIALLY NO INCREASED DRY CREASE RECOVERY TO SAID MATERIAL, THE IMPROVEMENT WHICH COMPRISES CONDUCTING SAID CROSS LINKING REACTION WHILE SAID MATERIAL IS WET WITH AN AQUEOUS SOLUTION CONTAINING AT LEAST 10% BY WEIGHT OF A TRIALKALIMETAL PHOSPHATE WHEREBY SAID TEXTILE MATERIAL HAS IMPARTED THERETO BOTH IMPROVED WET AND DRY CREASE RECOVERY PROPERTIES. 